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GPS Data+Time=EXIF Data Accuracy

PatR

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A recent requirement to start correlating CGO3+ EXIF photo data with Google Earth imagery revealed a new reason to allow a little extra time between when the H indicates it is ready to fly to when you actually lift off. After reviewing quite a few photos and comparing them with the GPS location provided in the EXIF data it became apparent that something was not right with the GPS location data for some of them. Some of the GPS coordinates placed the H miles away from the location the photo was actually shot, while other photos provided GPS data that depicted the location with reasonable accuracy. What the heck?

Some Google searches provided several articles related to EXIF data and GPS positional accuracy and it appears that GPS accuracy presented in EXIF data is relative to how much time a camera has been permitted to remain on prior to shooting pictures. Oh my, where have we read of this before;) As with other devices using GPS, positional accuracy increases over time. Looking again though the groups of photos I remembered some of the locations where the H was given very little time to warm up between "ready to fly" and T/O before capturing images, and locations where several minutes was provided between "ready to fly" and lift off. Reviewing the GPS data from those photo shoots again in Google Earth showed the first photos in a series from locations where the H was provided some "warm up" time before flight were always location accurate while the first photos in a series where the H was not provided any warm up time were consistently showing locations quite a bit distant from the shoot location. Like many miles distant. The GPS position data for the spreads that were location inaccurate improved in accuracy as the number sequence increased in the photo spreads, or over time while the H was airborne, which established a direct relationship between time and position accuracy.

This may not be of much importance for most but if you must have accurate GPS position references for a paying client, understanding we need to allow the system time to develop position resolution could be the difference between getting paid for your work or watching the customer depart to find a new photographer. If you shoot for insurance companies, construction companies, or other businesses that require the location the GPS data you provide on the images might be a critical part of the deliverables package. What you give them will be a heck of a lot more accurate if you permit your H a little extra time to generate good position resolution before springing into the air.

Side note; Yuneec uses a "unique" GPS position format that is a bit of a P.I.T.A. to reconfigure to hours-minutes-seconds formatting recognized by Google Earth or Garmin. The conversion process is made easier with an EXIF converter program that can be downloaded. I'm currently using EXIF Pilot. Not the best or perfect but it works and is free. There are others.

As always, have fun doing what ya do.
 
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A recent requirement to start correlating CGO3+ EXIF photo data with Google Earth imagery revealed a new reason to allow a little extra time between when the H indicates it is ready to fly to when you actually lift off. After reviewing quite a few photos and comparing them with the GPS location provided in the EXIF data it became apparent that something was not right with the GPS location data for some of them. Some of the GPS coordinates placed the H miles away from the location the photo was actually shot, while other photos provided GPS data that depicted the location with reasonable accuracy. What the heck?

Some Google searches provided several articles related to EXIF data and GPS positional accuracy and it appears that GPS accuracy presented in EXIF data is relative to how much time a camera has been permitted to remain on prior to shooting pictures. Oh my, where have we read of this before;) As with other devices using GPS, positional accuracy increases over time. Looking again though the groups of photos I remembered some of the locations where the H was given very little time to warm up between "ready to fly" and T/O before capturing images, and locations where several minutes was provided between "ready to fly" and lift off. Reviewing the GPS data from those photo shoots again in Google Earth showed the first photos in a series from locations where the H was provided some "warm up" time before flight were always location accurate while the first photos in a series where the H was not provided any warm up time were consistently showing locations quite a bit distant from the shoot location. Like many miles distant. The GPS position data for the spreads that were location inaccurate improved in accuracy as the number sequence increased in the photo spreads, or over time while the H was airborne, which established a direct relationship between time and position accuracy.

This may not be of much importance for most but if you must have accurate GPS position references for a paying client, understanding we need to allow the system time to develop position resolution could be the difference between getting paid for your work or watching the customer depart to find a new photographer. If you shoot for insurance companies, construction companies, or other businesses that require the location the GPS data you provide on the images might be a critical part of the deliverables package. What you give them will be a heck of a lot more accurate if you permit your H a little extra time to generate good position resolution before springing into the air.

Side note; Yuneec uses a "unique" GPS position format that is a bit of a P.I.T.A. to reconfigure to hours-minutes-seconds formatting recognized by Google Earth or Garmin. The conversion process is made easier with an EXIF converter program that can be downloaded. I'm currently using EXIF Pilot. Not the best or perfect but it works and is free. There are others.

As always, have fun doing what ya do.

Good afternoon friend. How are you?
I work with topography, and I have a Phantom 4. However I am thinking of buying a TH. I would like to know if the properties of the photos show the EXIF data, because I work with ortomosaics, and I need these data for the planimetric survey. Could you send a photo taken by your TH so I can evaluate the content?
Thank you for your attention.
A hug!
 
A recent requirement to start correlating CGO3+ EXIF photo data with Google Earth imagery revealed a new reason to allow a little extra time between when the H indicates it is ready to fly to when you actually lift off. After reviewing quite a few photos and comparing them with the GPS location provided in the EXIF data it became apparent that something was not right with the GPS location data for some of them. Some of the GPS coordinates placed the H miles away from the location the photo was actually shot, while other photos provided GPS data that depicted the location with reasonable accuracy. What the heck?

Some Google searches provided several articles related to EXIF data and GPS positional accuracy and it appears that GPS accuracy presented in EXIF data is relative to how much time a camera has been permitted to remain on prior to shooting pictures. Oh my, where have we read of this before;) As with other devices using GPS, positional accuracy increases over time. Looking again though the groups of photos I remembered some of the locations where the H was given very little time to warm up between "ready to fly" and T/O before capturing images, and locations where several minutes was provided between "ready to fly" and lift off. Reviewing the GPS data from those photo shoots again in Google Earth showed the first photos in a series from locations where the H was provided some "warm up" time before flight were always location accurate while the first photos in a series where the H was not provided any warm up time were consistently showing locations quite a bit distant from the shoot location. Like many miles distant. The GPS position data for the spreads that were location inaccurate improved in accuracy as the number sequence increased in the photo spreads, or over time while the H was airborne, which established a direct relationship between time and position accuracy.

This may not be of much importance for most but if you must have accurate GPS position references for a paying client, understanding we need to allow the system time to develop position resolution could be the difference between getting paid for your work or watching the customer depart to find a new photographer. If you shoot for insurance companies, construction companies, or other businesses that require the location the GPS data you provide on the images might be a critical part of the deliverables package. What you give them will be a heck of a lot more accurate if you permit your H a little extra time to generate good position resolution before springing into the air.

Side note; Yuneec uses a "unique" GPS position format that is a bit of a P.I.T.A. to reconfigure to hours-minutes-seconds formatting recognized by Google Earth or Garmin. The conversion process is made easier with an EXIF converter program that can be downloaded. I'm currently using EXIF Pilot. Not the best or perfect but it works and is free. There are others.

As always, have fun doing what ya do.
Pat, has it to do something with the 12,5min "stay on the ground" Time to first fix - Wikipedia that was denied a while ago?
 
I hadn't really thought about the CGO3+'s GPS EXIF data before. Does anybody know where the CGO3+ gets the GPS data from? It seems like there are 4 possible scenarios:
1. The CGO3+ has its own GPS module inside it.
2. The ST-16 transmits its own GPS data to the CGO3+
3. The ST-16 re-transmits the Typhoon H's GPS data that it receives back out to the CGO3+
4. There is a serial connection on the CGO3+'s camera connector so it receives the GPS data from the Typhoon H's flight controller directly.

Items 1,4 seem prettty unlikely and it seems like I would have stumbled across that info already.
Item 2 would be the easiest for them to implement, but would be inaccurate (it would report where the pilot was in the EXIF, not where the drone was)
 
I hadn't really thought about the CGO3+'s GPS EXIF data before. Does anybody know where the CGO3+ gets the GPS data from? It seems like there are 4 possible scenarios:
1. The CGO3+ has its own GPS module inside it.
2. The ST-16 transmits its own GPS data to the CGO3+
3. The ST-16 re-transmits the Typhoon H's GPS data that it receives back out to the CGO3+
4. There is a serial connection on the CGO3+'s camera connector so it receives the GPS data from the Typhoon H's flight controller directly.

Items 1,4 seem prettty unlikely and it seems like I would have stumbled across that info already.
Item 2 would be the easiest for them to implement, but would be inaccurate (it would report where the pilot was in the EXIF, not where the drone was)
Could you tell me if you have the latitude and longitude information in the photo properties?
 
I have never looked, but from the OP it sounds like it is.
Look, this is the properties of a Phantom file, which I have. But I would like to know if the Thyphoon or Q500 has the same properties, because I want to buy one.
 

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has it to do something with the 12,5min "stay on the ground" Time to first fix - Wikipedia that was denied a while ago?

It certainly sounds like this could be the case. I have always advocated for this and the info Pat has provided seems to be backing this up.
 
Pat, has it to do something with the 12,5min "stay on the ground" Time to first fix - Wikipedia that was denied a while ago?

Sorry guys, I'm not getting this infatuation with "stay on the ground". There are literally hundreds of discussions at DIYDrones about GPS issues, EXIF, RTK, GCP etc. Seriously, only the problem GPS units needed to sit for several minutes before getting a fix. 3DR's demise.

This from 2014 at DIYDrones where I spent many hours at.
The new plug and play VRX GPS NEO-M8 MULTICONSTELLATION (GPS , GLONASS , GALILEO) with HMC5983
The NEO-M8 is a 72-channel high sensitive engine that boasts a Time-To-First-Fix (TTFF) of less than 1 second.

The dedicated acquisition engine, with over 2 million correlators, is capable of massive parallel time/frequency space searches, enabling it to find satellites instantly.

Innovative design and technology suppresses interference sources and mitigates multipath effects, giving NEO-M8 GPS receivers excellent navigation performance even in the most challenging environments.

VRX GPS NEO-M8 is equipped with a Panasonic Amplifier for better reception and a backup battery for quicker warm restarts.


Compare that to the Wikipedia link. What decade are they in?

Beating a dead horse.

The quality of the GPS data output from a drone is directly proportional to the quality of the GPS unit, the placement of the unit, the gimbal, the quality of the signal and the firmware/software that drive them. And remember, the GPS must work in sync with the compass heading. If they are in disagreement, there will be problems.

There will be GPS location error because if the vehicle is moving, there is lag. Also, GPS data in the Z direction (altitude) is notorious for being very inaccurate, which causes problems with terrain following. Let it sit for an hour to get "better" acquisition and it won't matter. There is inherent error anyway. Syncing the pictures with the true GPS coordinates is a problem. There are many things going on.

Why on earth did Yuneec use dynamic RTL by default? It should be an option.

Here are posts by Thorsten on GPS issues and tests he performed. Actually he does allow the GPS units to sit for up to 40 minutes to acquire a signal.......while INSIDE.
u-blox M8N - ground planes, antennas and positional accuracy
For the above test, he allows all units to run for 10 minutes before beginning recording. The xy scatter tells the story; no amount of time "sitting on the ground" can improve a substandard or defective GPS system. If it's prone to wondering, it will wonder.

Hopefully some will understand the point I'm trying to make.
Gi9bxXy.png
 
Look, this is the properties of a Phantom file, which I have. But I would like to know if the Thyphoon or Q500 has the same properties, because I want to buy one.

The photos taken with CGO-3 cameras on the H most certainly do contain Lat/Long coordinates in the EXIF data file. They are clearly seen when the “Properties” tab is clucked in the data file.
 
I hadn't really thought about the CGO3+'s GPS EXIF data before. Does anybody know where the CGO3+ gets the GPS data from? It seems like there are 4 possible scenarios:
1. The CGO3+ has its own GPS module inside it.
2. The ST-16 transmits its own GPS data to the CGO3+
3. The ST-16 re-transmits the Typhoon H's GPS data that it receives back out to the CGO3+
4. There is a serial connection on the CGO3+'s camera connector so it receives the GPS data from the Typhoon H's flight controller directly.

Items 1,4 seem prettty unlikely and it seems like I would have stumbled across that info already.
Item 2 would be the easiest for them to implement, but would be inaccurate (it would report where the pilot was in the EXIF, not where the drone was)

I’m going to relate something I’ve learned after extensive research for the 920 and some experience with the CGO-3 camera.

The CGO-3 position data recorded in EXIF files has to come from one of the sources listed in items 2, 3, or 4. After destroying a CGO-3 camera early on by trying to change lenses I know the camera does not have s GPS receiver in it.

When Yuneec elected to use parts of a Lumix to create the CGO-4 they decided to leave out some of the features available when using a CGO-3. EXIF geo position reference was one of them, along with team mode functionality. There has to be some type of data transfer between the auto pilot and the camera, that’s particular to the camera type, that fixes geo location in a photo file. If you hang a CGO-3 under a 920 you suddenly get geo position reference back in EXIF data that is not present when using a CGO-4. Strangely, team mode is returned to the 920 system when a CGO-3 is used. It is not available when using a CGO-4.

So there’s something extra in the CGO-3 software that obtains geo data from either the aircraft or ST-16. My vote goes to the aircraft.

Glider,

Why did Yuneec run with the GPS hardware they did? Easy answer is they got them cheap.
 
The NEO-M8 is a 72-channel high sensitive engine that boasts a Time-To-First-Fix (TTFF) of less than 1 second.
The dedicated acquisition engine, with over 2 million correlators, is capable of massive parallel time/frequency space searches, enabling it to find satellites instantly.
Gi9bxXy.png

Thanks for that insight, however, the issue is not solely related to just how fast the satellites can be found (regardless of the GPS unit), but more to do with the Almanac, and downloading the sufficient data prior to flight. As I have said before, if you fly regularly at the same location, then there is no need to wait for the Almanac each time, however, if you are flying in a different location, or haven't flown for around a fortnight (as a rule of thumb), then it is wise to sit a little longer on the ground for that first initial flight.

Beating a dead horse? not if it's name is Phar Lap.
 
Since I've made it my strategy to use a dedicated "non-flight" battery for functions such as GPS almanac downloading... I'll wait the occasional 10 minutes.

You can drag a dead horse to water, but you can't make him drink... ;)
 

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